A one-dimensional magnetic field sensor is known from U.S. Pat. No. 5,942,895, which comprises two horizontal Hall elements and two elongated magnetic field concentrators. The two magnetic field concentrators are separated by an air gap. The two Hall elements are arranged at the edge of the air gap and are coupled in an anti-parallel manner. The magnetic field sensor detects only one component of the magnetic field, namely the one which extends parallel to the longitudinal direction of the two magnetic field concentrators.
A two-dimensional magnetic field sensor is known from U.S. Pat. No. 6,545,462, which comprises at least two horizontal Hall elements and a disc-shaped magnetic field concentrator. The Hall elements are arranged beneath the edge of the magnetic field concentrator. The magnetic field sensor detects two components of the magnetic field, from which the direction of the magnetic field is determined.
A current sensor is known from European patent publication EP 1746426, which comprises a one-dimensional magnetic field sensor with one or two elongated magnetic field concentrators and at least one vertical Hall element.
The Hall elements are integrated in the active surface of a semiconductor chip, typically in CMOS technology, and the magnetic field concentrators are arranged on the active surface.
It is important in some applications of these magnetic field sensors, e.g. in current sensors, that the magnetic field concentrators produce a high amplification of the magnetic field to be measured on the one hand, since a high amplification factor means a relatively high signal-to-noise ratio or high resolution capability, and that the magnetic field concentrators on the other hand reach saturation only at the highest possible magnetic field strength so that the linear measuring range is as large as possible.